WASHINGTON — Senate Democrats on Wednesday began an effort to outdo President Trump on a signature issue: protecting American workers from foreign competition.

Democrats, outflanked by Mr. Trump in the 2016 presidential campaign, are seeking to recapture the loyalty of voters convinced that globalization is eroding their fortunes and prospects.

They introduced a set of proposals built around two ideas: preventing unfair foreign competition and providing government support for domestic industries.

The highlights include a new agency to prevent foreign investments that would harm the domestic economy, and tax incentives for “reshoring” jobs, or bringing jobs back to the United States, from overseas.

The political challenge for Democrats is that the proposals echo Mr. Trump’s ideas on trade. Even the rhetoric Wednesday had a distinctly Trumpian flavor.

“They’re rapacious, the Chinese,” declared Senator Charles Schumer of New York, the minority leader and moving spirit behind the proposals. “They do not play by the rules. And we sit there.”

But Mr. Schumer sought to draw a distinction between Democrats and Mr. Trump. “The problem is President Trump has talked a good game and done virtually nothing on trade but study it,” he said. “We need action. If President Trump wants to work with us to get things done, good.”

The proposals reflect the sharp change in the political debate about trade since the 2016 election. The Republican Party strongly supported increased trade in recent decades while Democrats made an uneasy peace with globalization. Now Mr. Trump has upended Republican dogma, and Democrats are embracing their own protectionist heritage.

The turn toward protectionism in the United States and other developed nations, notably Britain, has alarmed proponents of trade who argue that globalization has made the world wealthier, healthier and happier in recent decades. While acknowledging trade has disrupted the lives of many workers, experts caution that protectionist policies will not reverse the damage.

“I’m both saddened and furious that the Senate Dems have jumped on the protectionist bandwagon so fully, with all the rhetorical flourish” said Robert Howse, a law professor at New York University who specializes in international trade. “As a matter of policy, none of these measures, on any plausible economic theory, would result in improving the circumstances of U.S. workers, addressing inequality, or the socioeconomic challenges specific to the U.S. heartland.”

But politicians have taken Mr. Trump’s success as evidence that the political wind is blowing in a different direction.

“Anyone that believes that free trade is fair trade, come to West Virginia,” said Senator Joe Manchin, a Democrat from the state.

The first set of proposals was presented by a group of liberal congressional Democrats. On Wednesday, Mr. Schumer was joined by the more conservative members of his caucus, including Mr. Manchin and Senator Joe Donnelly of Indiana.

One recurring theme: new agencies. On Wednesday, for example, Democrats proposed the creation of a trade prosecutor to pursue complaints about unfair trade practices. The Office of the United States Trade Representative, and the Commerce Department, have similar responsibilities.

“America’s trade policies are not working for many working families and small businesses,” according to the plan’s introduction. “For too long, big corporations have dictated how trade deals and foreign acquisitions are negotiated and the American worker has been left without a seat at the table.”

Other proposals break new ground, like an American Jobs Security Council to review foreign investments in American companies. It is modeled on an existing body that prevents investments that undermine national security; the new body would be responsible for preventing “detrimental economic impacts.”

As an example, the plan says the council could have blocked the proposed purchase of the Chicago Stock Exchange by Chinese investors. The deal is under review by the Securities and Exchange Commission. Democrats also cited the proposed sale of Aleris, an Ohio aluminum company, to a Chinese rival.

Democrats also called for changes in the tax code to penalize companies that move jobs out of the country, and to reward companies that return jobs to the United States — particularly to rural and economically disadvantaged areas.

The Democratic proposals closely track Mr. Trump’s rhetoric in other areas. It backs the renegotiation of the North American Free Trade Agreement, known as Nafta. It calls for a crackdown on currency manipulation by foreign nations. It also would strengthen laws requiring taxpayer-funded projects to use American materials and services, just like Mr. Trump’s staple “Buy American” theme.

“Taxpayer money should not be spent on foreign products like iron and steel from China and Russia,” said Senator Tammy Baldwin, Democrat of Wisconsin.

The proposal highlights the odd politics of the current moment. Ms. Baldwin has introduced “Buy American” legislation, and Mr. Trump has endorsed it, but it does not have the support of the rest of Mr. Trump’s party.

Follow Binyamin Appelbaum on Twitter @bcappelbaum.

A version of this article appears in print on , on Page B3 of the New York edition with the headline: Senate Democrats Seek To Outdo Trump on Trade. Order Reprints | Today’s Paper | Subscribe